The influence of spatial discretization on HEC-HMS modelling: a case study

Abstract

The spatial discretization of a watershed can directly influence the derived outputs of hydrological models? Conclusive guidelines regarding the proper level of spatial discretization have not yet been established due to the great diversity of models, calibrated parameters and topographic and geospatial characteristics of study areas. The objective of this study was to investigate the influence of different levels of watershed spatial discretization (2, 4, 8, 16 and 32 sub basins) on the HEC-HMS model's performance, considering the Environmental Protection Area (APA) of the Uberaba River Basin region. The SCS-CN method was applied to the different levels of spatial discretization for two distinctive periods (calibration and validation) and its performance was evaluated according to seven goodness-of-fit measures: MAE, RMSE, RSR, NSE, PBIAS, R2 and KGE. The results obtained from a qualitative and quantitative perspective, based on the visual analysis of the simulated hydrographs and the obtained goodness-of-fit values; indicate the HEC-HMS model represents the hydrological processes of the basin under investigation efficiently, regardless of the level of spatial discretization. The results suggest the subdivision of a watershed does not result in improvement of the HEC-HMS model's performance without significant differences in physiographic characteristics (slope, land use and types of soil). Considering its good performance for the study area, it is suggested the application of the HEC-HMS model for future works that aim to investigate the drainage capacity of the APA of the Uberaba River.

Model Calibration Parameter Using Optimization Trial in HEC-HMS for Unda Watershed

“…Percent bias is expressed in relative terms so that it is possible to evaluate the size of the bias due to under coverage for the parameters that are not known to be estimated. In the initial model, the PBIAS value was 44.70%, classified as unsatisfactory and decreased from 80.24% to 24.80% at calibration, classified as satisfactory [17]. Several parameter values have changed; namely, the lag time value for SB-1 changed from 8357.25 minutes to 29715 minutes.…”

Daily Simulation of the Rainfall–Runoff Relationship in the Sirba River Basin in West Africa: Insights from the HEC-HMS Model

“…The ALOS PALSAR DEM data were hydrologically processed within the ArcHydro tool [59] to delineate the SRB catchment and subcatchment boundaries along with their physical and morphometric characteristics such as average longitudinal slopes, area, flow path length, reach segment and centroid location. Following [60], to account for spatial variability in soil surface conditions in this study, a subdivision into homogeneous subcatchments was carried out. In total, 12 subcatchments, ranging from 1548.1 to 6992.4 km 2 in size, were defined, as presented in Figure 4.…”